Molecular cloning of cDNAs for the rat interleukin 2 receptor alpha and beta chain genes: differentially regulated gene activity in response to mitogenic stimulation.

We have isolated, by transient expression and screening using an oligonucleotide probe, cDNA clones encoding the rat interleukin 2 receptor (IL 2R) alpha and beta chains, respectively. Both chains are approximately 60% identical at the amino acid level to their human counterparts. In common with the human and mouse IL 2R beta chains, the rat beta chain is a member of the cytokine receptor family. The rat IL 2R beta chain contains no conventional signal transduction machinery and, like the mouse IL 2R beta chain, has a significant number of deletions in its cytoplasmic tail in comparison to the human protein. Northern analysis indicates that the rat beta chain message is constitutively transcribed in normal resting lymphocytes, whereas the alpha chain message is absent. Transcription of both chains of the receptor is up-regulated by cellular activation. However, kinetic studies have shown that whereas alpha chain message is rapidly induced, and can be detected 5 h after the addition of phytohemagglutinin, levels of beta chain mRNA increase at a much later time point and are not seen to rise until approximately 24 h after the addition of mitogen. These data suggest that the expression of high-affinity IL 2R is controlled by factors which influence transcription of both the alpha and the beta chain genes.